can i export 3d image from vr drawing

Question

These Wikipedia images should make it clear:

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You lot desire to describe an image which is distorted like the right one. Your VR arrangement will map information technology onto a sphere like in the left and the system user watches information technology sitting in the midpoint of the sphere.

You lot "simply" accept a rectangular expanse which is ii times every bit wide equally it's high. You desire plainly draw space dust, stars and maybe some imagined planets, too.

Put the items into the rectangle, but you lot must determine the right scaling. Vertically there's needed no scaling. But horizontally you must stretch the items. The more stretching the further the item is from the equator. Single points, the n and due south poles will make full alone the top and the bottom edges of the rectangle. Small items on the equator could be drawn as is without fault.

In theory you tin can draw without stretching and with mathematical transform you can create the stretched image. The greenish expanse shows how much room you take:

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If you insert the items into dark-green expanse, cut information technology to small horizontal slices and stretch every green part every bit wide every bit the rectangle, you have the wanted equirectangular image.

The exact form of the edge of the green area is a one-half cycle of cosine curve (information technology's the same equally sine bend, only shifted)

If you lot do the stretching to both directions, the job can seem subjectively easier:

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In both cases the total stretching is the same (=zero at the equator, one point to whole image width at the poles).

The practical drawing onto the greenish area is extremely difficult, considering only very small items do not get distorted.

Drawing tin can be helped with lines which will become horizontal and vertical in the stretched prototype and nowadays meridians and parallels on the world map.

Parallels in unstretched paradigm are the same as in the stretched image, simply meridians are differently scaled cosine curves:

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The stretching is possible in programs which have mapping with custom equations. The mapping takes content to betoken (x,y) in the stretched image from unstretched image point (ten',y'), where y' =the same y and 10' =(W-1)/two + (x-(West-ane)/2)cos(Pi(y-(H-1)/2)/(H-i)).

W and H are the epitome size in pixels, the coordinates are assumed to take ranges from 0 to (Westward-1) and (H-1). This is for bidirectional stretching, 1 directional stretching has nearly aforementioned formula , only replace (Westward-i)/2 with (Westward-1).

This is the stretched epitome and the stretching dialog in Affinity Photo:

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The numbers reflect the dimensions Due west=3000, H=1500. Every bit a photo this could be quite high resolution, simply for this it's besides coarse - as you see, polar areas are fuzzy. The image should contain abrupt rectangles.

Placed on the sphere the result is a little cleaner due the pinched polar areas, but withal far from the platonic:

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I tested besides bodily drawing. Directly as stretched information technology was hopeless, cypher became recognizable near poles and the residue was (at best) laughably distorted, when the issue was projected on a sphere.

Filling the light-green area earlier stretching worked marginally improve, if the meridians and parallels were in identify for reference, but in practice it was likewise hopelessly non-productive.

ADD: User Gerald Falla has told in his reply how it should be done. Nosotros can try it.

Actually Affinity Photo has live equirectangular mapping. One makes an empty cartoon say 3000 px wide and 1500 px loftier, fills information technology (if needed) with squares for easier orientation and goes to layer live equirectangular projection way. There he tin pigment the shapes, simply for feedback he watches the sphere from the centerpoint.

There should be no trouble to get the shapes fatigued undistorted, if the person can draw well on normal aeroplane. The drawing generates under the hood the correct equirectangular paradigm.

At first we have 3000x1500 px bitmap image with rectangular grating. The equator and the goose egg-elevation are blood-red.

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